Engine starter jaw meshing device



Oct. 11, 1955 R. J. NIEMELA 2,720,299

ENGINE STARTER JAw MESHING DEVICE Filed oct. 14, 195o FEM/@ INVENTOR.

REINO J, NIEMELA ATTORN EY United States Patent Ofiice 2,729,299Patented Oct. 11, 1955 ENGINE STARTER `TAW MESHING DEVICE Reino I.Niemela, Cleveland, Ohio, assigner to Jack & Heintz PrecisionIndustries, Inc., Cleveland, Ohio, a corporation of Delaware ApplicationOctober 14, 1950, Serial No. 190,179

1 Claim. (Cl. 192-104) This invention relates to engine starterassemblies and has for one of its primary objects to provide an improvedmeans for effecting engagement and disengagement of the jaws of theengine starter and the engine crankshaft.

' It has heretofore been the conventional practice to so mount thestarter that its jaw remains normally out of perature conditions causingcongealed lubricants. It

often occurs that the starter jaw extension operation fails and evenwhen the starter jaw is fully extended it meets head-on with the teethof the engine crankshaft jaw so as to fail to mesh properly foreffecting the proper engine cranking operation which causes increasedimpact torque. Moreover, in many instances, after cranking and enginefiring has been eifected, the starter jaw retraction operation fails,both as `to retraction and also as to prevention of the undesiredsubsequent starter jaw extension into mesh with the engine crankshaftjaw which latter is rotating under high speed while the engine isrunning. This causes the jaws to ratchet which results in destruction ofthe jaw teeth and engine bearings.

It is therefore one of the primary objects of my invention to provide inan engine starter assembly means whereby the starter jaw is normally inengagement with the engine jaw so as to be in position to initiate the;cranking operation upon energization of the starter motor and to alsoprovide an automatic means for disengaging the starter and engine jaws.

It is `therefore one of the primary objects of my invention to providein an engine starter assembly means whereby the starter jaw is normallyin engagement with the engine jaw so as to bein position to initiate thecranking operation upon energization of the starter motor and to alsoprovide an automatic means for disengaging the starter and engine jaws.

Another object is to provide such an automatic jaw disengaging meansthat normally permits jaw engagement at rest and during the crankingoperation, but which in response to a predetermined speed of rotation ofthe crankshaft of the engine after the latter has been started, acts topositively disengage the jaws.

Another object is to provide such a speed responsive jaw disengagingmeans in the form of a centrifugally responsive clutch that disengagesthe jaws and maintains them disengaged as long as the speed of rotationof the engine crankshaft is equal to or greater than a predeterminedspeed.

A further specific object is to provide such a jaw disengagingcentrifugal clutch, as a separate self-contained package, that may beconveniently secured to and carried by the engine crankshaft, withoutredesign of the latter, and that will permit ready attachment of thestarter with the two jaws initially in mesh with no need of any starterjaw extension or retraction means being incorporated in the enginestarter.

With the foregoing and other objects in view, the invention resides inthe combination of parts and in the details of construction hereinafterset forth in the following specification and appealed claim, certainembodiments thereof being illustrated in the accompanying drawings, inwhich:

Figure l is a View in longitudinal section taken through one end of theengine crankshaft, the centrifugal spring clutch, its jaw and that ofthe starter in mesh with each other;

Figure 2 is a similar View showing the clutch centrifugally operated, inresponse to engine speed, to disengage the two jaws;

Figure 3 is a fragmentary view in section taken through the engineflange and starter pad, showing the crankshaft and starter shaft and themeshing jaws in side elevation;

Figure 4 is an end view of the clutch, partly broken away to show thecentrifugally responsive balls; and

Figure 5 is a view in perspective of the adjacent jaws, shown unmeshed.

Referring more particularly to the drawings, for purposes ofillustration, I have omitted showing the engine starter, itself, buthave shown the driven. starter cranking shaft 1 carrying a dog type jaw2. The starter construction itself may be of the type disclosed ineither of the United States patents to Ralph M. Heintz for Starter JawMeshing Mechanism No. 2,513,937, July 4, 1950, and No. 2,509,767, May30, 1950, with the exception of the actual starter jaw and engine jawmeshing mechanisms to which my invention is directed in making animprovement thereon. At 3, I have shown one end of the hollow enginecrankshaft. Without any redesign of the hollow crankshaft, I secure aplug 4, maintained against longitudinal movement by a snap ring 5.

As shown in Figure 3, the engine crankshaft 3 is rotatably supported forrotation in a bearing 6 in the engine flange 7. The starter shaft 1 issupported for rotation in a bearing 8 in a starter pad 9 that isreleasably secured to the engine ange 7 by screw bolts 10 and nuts 11.

The automatic centrifugal jaw engaging and disengaging clutch comprisesa main hollow sleeve 12 provided with external longitudinal splines inthe hollow crankshaft 3, so as to permit longitudinal movement, butprevent relative rotation of, the clutch sleeve 12 in the hollowcrankshaft 3. Integral with sleeve 12 is an enlarged head 13 to which issecured by a snap ring 14 a relatively stationary ring 15. The front, orright, face of this ring 1S is provided with a compound angular ramp 16.Slidably mounted on the head 13 is a concave ring 17. The front, orright, end of the clutch head 13 terminates in a jaw 18, to mesh withjaw 2 carried by a starter shaft 1. The front end of ring 17 is providedwith a spider frame including four radial ribs 19 joined to a commonapertured center ring 20. The front face segments 18 of the clutch headis provided with slots 21 to loosely receive the ribs 19 and also toreceive the prongs 2 of the starter jaw.

The clutch assembly is secured in place in the plug 4 in the hollowcrankshaft by means of a screw bolt 22, whose left end screws into theplug. The other end of the bolt 22 extends through ring 20 and isprovided with a retaining head 23. Surrounding bolt 22 is a compressioncoil spring 24, whose expansive force may be adjusted by a nut 25screw-threaded on bolt 22. Arranged so as to be retained, and in surfacecontact with, the ring 17 and the ramp 16 of ring 15, are a series ofcir- 3 cularly arranged metal balls 26, under the resilient force ofspring 2,4.

With the clutch assembly thus assembled and slidably secured in thecrankshaft plug, and the crankshaft being rotatably supported by bearing6 in the engine ange 7, the starter pad 9, carrying the starter shaft 1,is secured to the engine flange, as shown in Figure 3. As shown both inFigures l and 3, when this connection is made, the two jaws 2 and 18 areinitially in mesh. Thus, when the conventional vstarter motor isenergized, its shaft 1 is rotatably driven, and, inasmuch as its jaw 2is in mesh with jaw 18, the clutch assembly and the engine crankshaftare rotatably driven. There is no problem of extending the starter jawinto mesh with the engine jaw, as is the case in conventional jawmeshing apparatus, because the starter is clamped` on in such a mannerthat the jaws are initially in mesh. Thus in the engine cranking cycle,and up until the time the engine tires, as long as the motor remainsenergized, the cranking operation continues.

I have found that it is imperative that some means be provided fordiscontinuing cranking after the engine fires and attains a speedgreater than that of the starter drive shaft. This I propose toaccomplish by means that is automatically responsive to the speed ofrotation of the engine after the latter has red and is self-driven.Accordingly, in order to accomplish this, I further propose to providemeans whereby the jaws become automatically disengaged upon apredetermined engine speed, greater than that of the starter driveshaft, and automatically engaged below such predetermined engine speed.This is attained by the provision of the clutch assembly abovedescribed. In detail, the particular engine crankshaft speed responsivecentrifugal clutch assembly unit is so designed that, after enginefiring, and high engine speed is attained, the centrifugal balls 26exert radially outward force. They ride outwardly on the inner face ofring 17 and also angularly outwardly on the compound ramp 16 of ring 15,as shown in Figure 2. The resultant eiect of this centrifugal action isto spread the two rings 1S and 17 apart, forcing ring 15 and the clutchsleeve 12, 13 to the left, against the action of spring 24. Thisreleases jaw 1'8 from mesh with starter jaw 2. Thus the enginecrankshaft is relieved from the drag of the starter shaft. Moreover,this is true even if the operator inadvertently continued to keep thestarter operating.

It follows that when the engine stops, or when 1it reaches apredetermined low speed of crankshaft rotation, the centrifugal actionon the balls lessens, permitting them to radially recede, assisted bythe action of spring 24, to again bring the jaws 2 and 18 into meshagain, as shown in Figures 1 and 3.

It is to be understood that, While I have shown dog type jaws, yI mayprefer to employ ratchet type jaws. In my preferred embodimentillustrated it will be seen that the starter, itself, need not containany means for extending or retracting its jaw. The starter jaw is merelycarried by the motor driven shaft for pure rotational drive and does notmove linearly in either direction. This eliminates heavy, expensive andcomplicated jaw meshing mechanism and its attending mechanical features.The starter is merely clamped into position with its jaw initially inmesh to drive the engine crankshaft directly and immediately uponorganization of the starter motor.

My preferred embodiment disclosed comprehends the use of an automaticclutch assembly, in the form of a simple, light, inexpensive and eicientunit, as a separate package. Its use calls for no redesign of thestarter or engine. It may be merely removably secured to the hollowengine crankshaft. The clutch unit, whether made and sold as a separatepackage or initially secured to the starter or engine crankshaft, stillcalls for no redesign of either.

I claim:

In combination in an engine starting apparatus, a rotary and linearlystationary starter cranking shaft and a toothed jaw rigidly carriedthereby, a rotary engine crankshaft and a complementary toothed jawdetachably longitudinally slidably splined therein, spring means forinitially and normally slidably extending the teeth of said engine jawaxially directly into mesh with the teeth of said starter jaw tonormally engage said jaws, and actuating means mounted independently ofthe teeth of said jaws and centrifugally responsive to a speed ofrotation of said engine crankshaft in excess of that of said startercranking shaft for retracting said engine crankshaft jaw out of meshwith said starter cranking jaw, lsaid actuating means being carriedsolely by said engine crankshaft jaw and comprising a pair of rings withopposed generally concave faces, one of which is ramped, and a series ofballs therebetween, one of said rings being rigid with said engine jawand the other ring being under resilient tension of said spring meansagainst said balls, said balls being normally urged radially inwardly insaid clutch means as said spring means normally forces said enginecrankshaft jaw slidably into mesh with said starter cranking jaw, saidballs, in response to a predetermined speed of rotation of said enginecrankshaft, after engine firing, being adapted to be centrifugallythrown radially outwardly up the ramp of one of said ring faces tospread the clutch rings apart and slidably retract said enginecrankshaft jaw axially away from and out of mesh with said startercranking jaw.

References Cited in the le of this patent UNITED STATES PATENTS1,105,408 Dechamps July 28, 1914 1,145,656 Apple July 6, 1915 1,219,698Brackett Mar. 20, 1917 1,490,505 Breese Apr. 15, 1924 1,739,150Honigmann Dec. 10, 1929 1,753,825 Ford Apr. 8, 1930 2,464,675 Dodge Mar.15, 1949 2,587,712 Dodge Mar. 4, 1952

